Means for producing curve-threaded nuts



June 36, 1931. E. HELIN ,1

MEANS FOR PRODUCING CURVE THREADED NUTS Filed Oct. 22. 1929 2Sheets-Sheet, 1

E/' h e/ ATTOR rrEfS m. 3 w 9 E 9 7 F v F 4 m 1 0 w Y 5T 2:25:55 m y muv n {.rli 4 EEEE= D 1 E. HELIN I MEANS FOR PRODUCING CURVE THREADED NUTSFiled Oct. 22, 1928 2 Shaw-Sheet 2 73 R rYE Ys A 1 I vii 1 w W. l v 1 .5A w -n$- Patented June 30,

ms HELIN, or STOCKHOLM, swEnnN; Assmnon To CARL mammalia f.srrooKnonmsWnnnn, t J

' MEANS FOR rnonnome onnvn-rnnnnnnnnnrs Applicationfiled ctober'22 1929, Serial nolfaorgna, and in stvedenjiuly 5,1921 I Experience has shownthat a curve-threaded nut can be produced by means of a screwtap on theconditions that the tap be tapered [and provided with cutting teeth ofequal height and equally spaced 1n the subsequent series, thetops ofthe,teeth"lying on lines the present inventions-' show two forms of thescrew-tap, Figsi 4 to 6 and 7 to 9, respectively, showthe'prog-ressofthe ,thread-cuttingiintwo special cases In the form of constructionshown in Fig.

- 1, the nut-blank 1 is inserted in a slide-block which are thoughtdrawn from the wider base toythe narrower top of the tap,-'these linespreferably being in-the form ofarcs, whose radii correspond'to theradius of the desired curvature of the thread, and that the nut-blank inrelation tothe'rotating screw-1 tap be fed parallel to itself along anarc corresponding to the curvature of the thread.

' 35 During the cutting operation, each tooth will at each revolutionrise through a zone at right an thi ough which passes the last tooth ofthe 1% to the axis of the tap, andthose zones .base of the tap andwhich. determines the no depthiofthe thread, will innoother way differfrom slmilar zones in an-ord'inary straight nut cut by means ofascrew-tap than that the walls of the zonesiare at two opposite sidesbent to a small portion of the curvature of .thethread, which isof noprac tical significance. 1

The present'nvention relates to a curvethreaded nut to be used as alock-nut without the use of any other auxiliary. means as for '30instance counter-nut, elastic ring, fibre packing or the like, givingnevertheless a definite and positive locking effect. p t 1 According totheinvention a curve-thread.- ed nut is'produced from an ape-rturednutblank by thread-cutting said nut-blank .by

1 parallel arcs.

means of a tapered screw-tap; by imparting to the nut-blank and thescrew-tap a relative motion composed of avrotary movement, a;

rectilinear movement and a reciprocating 2 which, in relation to therotating screw-tap on the supportof the spindle' driving the {withthe'same radius "as thedes'iredcurve' of "Wider base lOrand anarrowertop' ll with A :its greatest .corediameter at the base. The

3, is :setin movement laterally by a curved portion 4 of one ortwoguide-bars 5 fixed screw-tap 3. The tap has two axial guiding ins6,7,one of which is fixed in a chuck'8,

while the other runs ina'bushing 9 in the bed supporting theslide-blockQ. I

Other known arrangements for imparting 65 themutual movements to thenut-blank and the screw-tap may, of course, also be used, AsshowninFigs.2 and 3, the tops ofthe cutting teeth of'the screw-tap follow an arc thethread,.an'd the teeth arel'all ofithesame I height, i. e; their topsand bottoms follow The number of theteeth may 1 vary.

As shown in. the drawings the tap has a.

curvature of the arcs formed by the topsof the cutting teeth of the tapmay also be greatl er than that of the -'desired curvature of the.thread.

'The nut-blank has a central hole, which maybe bent'to the desired arc,as shown. in Figs. 4 to 6, or, as showninFigs.7 to 9',"the hole in thenut-blank '13 may be straight. In the former case the diameter of thecentral hole is equal to the base core: diameter of the tap. In thelatter case, the diameter of a the hole is'furtherlreduced by a layercorre-" 49 movement perpendicularjto said rectilinear' movement.Preferably the screw-tap performs the rotary movement and the rectilin-"ear movement, whereas the} nut-blank is adapted to perform thereciprocating move{ ment.

suited for carrying out the method.

In the accompanying drawings,';Fig. 1 is a V schematic view of a f'ormofconstruction of 50 an apparatus forcutting a nut according to Theinventionalso relates to a screw-tap sponding tothe height of thethread-curve-se The process of cutting the nut isshown in Figs. 4to 9inclusive showing the nut blank 7 and the screw-tap in section insuccessive relative positions,Figs. 4 to 6 showinga tap 14 i g of, thetype shown in Fig. 3, on which the teeth lie on inwardly curved arcs,whereas, Figs; 7 to 9 show a tap 15 of the type shown 'lI1 Fig. 2, onwhich the teeth lie on outwardly a curved arcs;

' Having now described my invention, what I claim as new and desire tosecure by Letters Patent is 1. A screw-tap for cutting curve-threadednuts, said tap provided with cutting teeth extending over a portionhaving a wider base and a narrower top with its greatest core diameterat the base, the tops of the cutting teeth of the tap lying on arcs of acurvature at least equally as great as the desired curvature of thethread.

2. A screw-tap for cutting curve-threaded nuts, said tap having atapering working portion provided with cutting teeth, the tops 4 of thecutting teeth lying on arcs curved inwardly and of a curvature at leastequally great as the desired curvature of the thread. In testimonywhereof I have signed my name to this specification.

ELIS HELIN.

